FePt-Si-N nano-granular thin films with improved structure and magnetic properties for high-density recording medium

► Small thickness and appropriate Fe content benefit perpendicular orientation. ► Ordering temperature for FePt-Si-N films is ∼100 °C higher than that of FePt films. ► Both FePt and FePt-Si-N films have the highest coercivity at Fe content of 55 at%. ► Doping Si-N improves coercivity by reducing exchange coupling and grain size. ► Si/N ratio has to be well controlled to achieve high coercivity in FePt-Si-N film.